1. Field of the Invention
The present invention relates to an image processing apparatus for obtaining image data for outputting, by carrying out predetermined image processing of image data obtained by optically reading an image recorded on a film.
2. Description of the Related Art
In recent years, a technique is known in which frame images recorded on a photographic film are optically read by a reading sensor such as a CCD (charge coupled device) or the like, image processing such as enlargement and/or contraction, various corrections, or the like is performed with respect to digital image data obtained from the aforementioned reading, and an image is thereby formed on a recording material by using laser light which is modulated on the basis of digital image data for which the image processing has been completed.
In such a technique in which frame images are digitally read by the reading sensor such as the CCD or the like as described above, in order to realize highly accurate image reading, frame images are read preparatorily (so-called prescanning), reading conditions in accordance with densities or the like of frame images (for example, amount of light to be irradiated onto the frame images, time during which charge is accumulated in the CCD or the like) are determined, and the frame images are again read on the basis of the determined reading conditions (so-called fine scanning).
At the time of photographing using a camera, there are some cases in which an electronic flash is used. If photographing is carried out having emitted the electronic flash, although the light amount can be forced to increase, because the electronic flash has light distribution characteristics (distribution of a light amount), there is a tendency in which the light-dark contrast between the central portion and the peripheral portion of the image increases such that a main subject (a person) located at the center of the image becomes whitish while the peripheral background becomes dark, for example.
In this case, if the electronic flash is of a type to be loaded into a comparatively expensive camera, light amount can be adjusted, a light diffusing plate can be placed so as to make a light amount distribution even, and indirect lighting can be carried out.
However, especially in the case of an LF (lenticular film: film equipped with lens), since the electronic flash is designed to increase the light amount irradiated onto the main subject (because the light amount is concentrated at the image central portion, where the probability is high that the main subject is located thereat), a large difference is thereby caused between light distribution characteristics corresponding to the photographing distance between a photographer and the main subject and light distribution characteristics corresponding to the photographing distance between the photographer and the background.
FIG. 6 is a side view of a scene where a photographer 102 is taking a picture of a subject (person) 104 by locating the subject 104 as a center. A wall 106 is placed behind the subject 104.
In this case, a photographing distance d from the photographer 102 to the subject 104 and a photographing distance dxe2x80x2 from the photographer 102 to the wall 106 have a relationship of d less than dxe2x80x2.
When the photographer 102 takes a picture, as is shown in FIG. 7A, the center of light distribution characteristics of an electronic flash 100S at a position of the subject 104 is located near an end of a shoulder of the subject 104 (see a point dc) while, as is shown in FIG. 7B, the center of the light distribution characteristics of the electronic flash 100S at a position of the wall 106 is located behind the neck of the subject 104 (see a point dxe2x80x2c). Namely, as the photographing distance becomes longer, the center of the light distribution characteristics of the electronic flash 100S moves closer to the center of the image photographed.
When the light distribution characteristics at the position of the subject 104, which is shown in the graph of FIG. 8A, and the light distribution characteristics at the position of the wall 106, which is shown in the graph of FIG. 8B, are compared to each other, it can be clearly seen that the light distribution characteristics at the position of the wall 106 are darker.
If there is such a light-dark contrast between the main subject and the background of an image, the image is not preferable.
In consideration of the aforementioned facts, it is an object of the present invention to provide an image processing apparatus that can reduce the light-darkness contrast between the main subject and the background when the image, which is photographed by a camera by using the electronic flash, is read optically.
A first aspect of the present invention is an image processing apparatus for obtaining image data for outputting, by carrying out predetermined image processing of image data, comprising: photographing information obtaining means that obtains light distribution characteristics of an electronic flash, corresponding to a photographing distance; computing means that reads the light distribution characteristics of the electronic flash, and computes a light amount adjusting amount of the image on the basis of the light distribution characteristics read; and correcting means that corrects the image on the basis of the light amount adjusting amount which is computed by the computing means.
In accordance with the first aspect of the present invention, the photographic information obtaining means obtains the light distribution characteristics of the electronic flash corresponding to the photographing distance. The computing means carries out light amount correction on the basis of the light distribution characteristics obtained.
When an image is photographed using the electronic flash, light distribution characteristics of the electronic flash vary in accordance with a photographing distance. Especially with an electronic flash having light distribution characteristics whose center is placed at the main subject of the image, the light amount of the background tends to decrease. Therefore, a feeling of visual disorder which is caused by the light amount difference between the main subject and the background can be mitigated by correcting the decreased light amount of the background through the aforementioned computation.
A second aspect of the present invention is an image processing apparatus for obtaining image data for outputting, by carrying out predetermined image processing of image data, comprising: photographing information obtaining means that obtains photographing information including light distribution characteristics of the electronic flash and the photographing distance of a camera; image separating means that separates the image into a main subject image portion and a background image portion; computing means that reads the light distribution characteristics of the electronic flash corresponding to the photographing distance to each of the main subject image portion and the background image portion, which have been separated from each other by the separating means, and computes a light amount adjusting amount of each of the main subject image portion and the background image portion on the basis of the light distribution characteristics thereof; correcting means that corrects each of the main subject image portion and the background image portion on the basis of the light amount adjusting amount which has been computed by the computing means; and combination means that combines the main subject image portion and the background image portion which have been corrected by the correcting means.
In accordance with the second aspect of the present invention, after the photographed image has been read optically, it is converted to, for example, a digital image. Therefore, it becomes easy to separate the main subject image portion and the background image portion from each other. As a result, the main subject image portion and the background image portion are corrected independently of each other (this includes the correction of only the background) thereby allowing the image processing apparatus to carry out more appropriate correction.
A third aspect of the present invention is an image processing apparatus according to the second aspect of the present invention, further comprising: density difference controlling means which controls the difference between densities of the contour of each of the main subject image portion and the background image portion when the main subject image portion and the background image portion are combined, to a predetermined value or less.
In accordance with the third aspect of the present invention, at the time of the combination of the above-described separated image portions, since the image processing apparatus of the present invention further comprises the density difference controlling means that controls the difference between densities of the contours of the main subject image portion and the background image portion to a predetermined density value or less, connecting portions of the combined images can be made smoother. For example, a weighting process is performed on the density of pixels adjacent to each contour of the image portions by the density difference controlling means, thus inhibiting extreme changes in the density.
A fourth aspect of the present invention is an image processing apparatus according to any one of the first to third aspects of the present invention, wherein the correction means includes setting means which sets a ratio with which correction can be substantially carried out in accordance with a density for each pixel when the image is expressed as a plurality of pixels.
A fifth aspect of the present invention is an image processing apparatus according to the fourth aspect of the present invention, wherein the ratio is set in accordance with a predetermined characteristics curve such that the ratio decreases as the density of the pixels becomes close to the base density of a negative image, the ratio increases as the density thereof becomes farther from the base density of the negative image, and the ratio continuously changes when the density is at the intermediate of the base density of the negative image.
In accordance with the fourth and fifth aspects of the present invention, in the photographic film (in a case of a negative film), if correction is performed on pixels whose density is close to the base density of the negative image, an unnatural picture pattern is formed. Accordingly, it should be noted that correction is not performed on the pixels whose density is close to the base density. Instead, the farther the density of a pixel is from the base density of the negative image, the more correction is performed. As a result, it becomes possible to remove the difference between densities of the main subject image portion and the background image portion without causing unnaturalness to the image as a whole.
In a case of a full-color image, the above-described correction can be performed on a color separation of R, G, and B, or, for example, R, G, and B colors can be corrected simultaneously by sampling illumination signals thereof.